The present invention relates to a method for manufacturing a semiconductor device; and, more particularly, to a method for forming a capacitor dielectric having a zirconium oxide layer and a tantalum oxide layer, and a method for manufacturing a capacitor using the capacitor dielectric.
A stacked structure of hafnium oxide (HfO2)/aluminum oxide (Al2O3)/hafnium oxide is conventionally used as a capacitor dielectric in a metal-insulator-metal (MIM) capacitor for enhancing capacitance and minimizing leakage current. Hafnium oxide is a high-dielectric-constant material with a crystalline phase, and aluminum oxide is a low-dielectric-constant material with an amorphous phase.
FIG. 1 is a cross-sectional view of a conventional capacitor structure. The conventional capacitor includes a lower electrode 11, a capacitor dielectric 12 having a stacked structure of HfO2/Al2O3/HfO2 disposed on the lower electrode 11, and an upper electrode 13 disposed on the capacitor dielectric 12.
Hafnium oxide increases the dielectric constant in the capacitor dielectric 12. However, the leakage current performance characteristic deteriorates when hafnium oxide crystallizes. Thus, the hafnium oxide should be cautiously crystallized in the conventional capacitor structure to achieve a favorable leakage current performance characteristic.
Furthermore, an amount by which the capacitance may be increased may be limited when using hafnium oxide for the capacitor dielectric. Hence, applying hafnium oxide to the capacitor dielectric is difficult when the design rule of the capacitor is reduced.